This application claims the benefit of Japanese Application No. 2000-251402 filed in Japan on Aug. 22, 2000, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a camera containing a finder mechanism that is driven forward and backward.
2. Description of the Related Art
Hitherto, Japanese Unexamined Patent Application Publication No. 11-212144 proposes a finder drive mechanism for a camera. This finder drive mechanism is arranged such that a lens frame is coupled with a finder cam through a gear and a finder optical system is driven forward and backward in association with the forward and backward rotation of the lens frame, and a phase adjusting friction clutch transmission mechanism is applied to the gear coupling unit thereof to adjust a phase.
It is possible to automatically execute phase alignment between a zoom lens barrel acting as a photographing lens barrel and a finder by utilizing the above-mentioned phase adjusting friction clutch transmission mechanism. Thus, it is not necessary to pay particular attention to the offset of an adjusted zoom position in assembly, which results in an effect of reducing man-hours in assembly and adjustment.
In the finder drive mechanism disclosed in Japanese Unexamined Patent Application Publication No. 11-212144, a finder cam is driven by a drive motor in association with the zoom lens barrel through a zoom drive gear mechanism, a finder drive gear mechanism, and a friction clutch mechanism so as to drive the finder optical system forward and backward. Since the finder cam requires a stopper that is abutted against a wide angle end and a telephoto end, the rotation angle of the finder cam is smaller than one rotation angle. Therefore, the variable power of a finder and a diopter scale are too sensitive to the rotation angle of the finder cam, which is disadvantageous to the accuracy of the camera including parts. Further, an increase in a zoom ratio increases the pressure angle of the finder cam, which is disadvantage in the amount of driving force.
In view of the aforementioned problems, an object of the present invention is to provide a finder drive mechanism to which a finder optical system having high variable power can be assembled and which can move forward and backward with a pinpoint accuracy, and to provide a camera containing the finder drive mechanism.
A finder drive mechanism of the present invention includes a finder cam assembly which has a rotating shaft and to which a cam is formed so as to drive a lens group in a finder optical system by rotation thereof; a rotation regulating member disposed around the rotating shaft of the finder cam assembly so as to be free to rotate in both directions; a rotation locking member disposed in a locus of rotation of the rotation regulating member for regulating a rotating range of the rotation regulating member to less than one rotation by being abutted against and locking the rotation regulating member; and an abutment section formed to the finder cam assembly and capable of being abutted against the rotation regulating member in a rotating direction thereof. In this finder drive mechanism, the finder cam assembly is operated in one of the following operating states according to the rotation thereof in both directions: an independently-rotating-state in which the abutment section is separated from the rotation regulating member and the finder cam assembly rotates independently; an integrally-engaged-rotating-state in which the abutment section is abutted against the rotation regulating member and rotates the rotation regulating member integrally with the finder cam assembly; and a locking state in which the rotation of the finder cam assembly is locked by locking the rotation of the rotation regulating member that is rotated in the integrally-engaged-rotating-state by the rotation locking member.
A camera of the present invention includes a variable power photographing lens barrel having a variable power photographing optical system; a drive source; a first driving force transmission means for transmitting a driving force from the drive source to the variable power photographing lens barrel; a finder optical system having a variable power function according to the variable power photographing optical system; a finder cam assembly having a rotational operation range of at least one rotation about a rotating shaft for driving a variable power lens group of the finder optical system by being rotated; a second driving force transmission means for transmitting the driving force from the drive source to the finder cam assembly of the finder optical system; a friction clutch means disposed to the second driving force transmission means; and a stopper means for regulating the rotational operation range of the finder cam assembly to a predetermined operation range of at least one rotation. In the above camera, the driving force from the drive source is transmitted to the finder cam assembly by the second driving force transmission means, and the rotating operation range of the finder cam assembly is regulated to a predetermined operation range of at least one rotation.
Further objects, features and advantages of the present invention will become apparent from the following description.